regex.h: Remove virtual class _Automaton.

regex.h: Remove virtual class _Automaton.

2013-10-20  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex.h: Remove virtual class _Automaton.
	* include/bits/regex_automaton.h: Likewise.
	* include/bits/regex.tcc: Adjust comment for policy changing.
	* include/bits/regex_executor.h: Update comments of complexity.
	* include/bits/regex_executor.tcc: Adjust executor choosing
	policy. Now DFS executor is the default one.
	* testsuite/util/testsuite_regex.h (regex_match_debug,
	regex_search_debug): Adjust for policy changing.

From-SVN: r203875